ThisCalculator

Everyday

Can’t Read Source File Disk? Fixes That Work

Updated · Standard formula, shown below

Can't Read Source File Disk? Fixes That Work

If you see “Can’t read source file or disk” when copying, moving, or opening a file, the error usually means Windows cannot access the file you specified. This guide explains the common causes and gives step-by-step fixes you can try right now.

What Causes This Error

The message appears when Windows tries to read a file but fails. It is not a single fault but a symptom of several possible issues:

  • File in use: Another program (like Word or a media player) has the file locked.
  • File path too long: Windows has a 260-character limit for file paths by default.
  • File name with invalid characters: Characters like :, *, ?, “, <, >, | are not allowed.
  • Drive not ready: A USB drive, SD card, or network drive is disconnected, unplugged, or asleep.
  • Permissions: You lack read access to the file or folder.
  • File corruption: The file or the disk has bad sectors.
  • Antivirus interference: Security software is blocking the read.

Identifying which cause applies to your situation is the first step to fixing it.

Quick Checks Before You Dig In

  1. Close any program that might be using the file (including preview panes in File Explorer).
  2. Check that the drive is properly connected. For USB, try a different port. For network drives, reconnect or restart your router.
  3. Try copying a different file from the same location. If that works, the issue is specific to that file.
  4. Restart your computer. This releases locked files and reinitializes drives.

These simple steps resolve a surprising number of cases. If the error persists, move on to the targeted fixes below.

Fix 1: Enable Long Path Support

Windows 10 and 11 have a hidden setting to allow paths longer than 260 characters. To enable it:

  1. Press Win + R, type gpedit.msc (Pro/Enterprise) or regedit (all editions), and press Enter.
  2. If using Group Policy: go to Computer Configuration > Administrative Templates > System > Filesystem > Enable Win32 long paths and set it to Enabled.
  3. If using Registry Editor: navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem and set LongPathsEnabled to 1.
  4. Restart your computer.

Alternatively, shorten the path by moving the file to a folder like C:\Temp (fewer characters) and try again.

Fix 2: Take Ownership and Check Permissions

If you don’t have read permission, Windows will show this error. To take ownership:

  1. Right-click the file or folder and select Properties.
  2. Go to the Security tab and click Advanced.
  3. Next to Owner, click Change.
  4. Type your username, click Check Names, then OK.
  5. Check Replace owner on subcontainers and objects and click OK.
  6. Go back to the Security tab, click Edit, select your user, and check Full control.

This is common after moving files from another computer or a previous Windows installation.

Fix 3: Scan the Disk for Errors

Bad sectors or file system corruption can cause read failures. Use the built-in Check Disk tool:

  1. Open Command Prompt as administrator (right-click Start > “Windows Terminal (Admin)” or “Command Prompt (Admin)”).
  2. Type chkdsk C: /f /r (replace C: with the drive letter of the problematic disk).
  3. If the drive is in use, you’ll be asked to schedule it for the next restart. Type Y and reboot.

For a USB drive, you can also right-click the drive in File Explorer > Properties > Tools > Check.

Fix 4: Rename or Move the File

Sometimes the file name itself is the problem. Try:

  • Renaming the file to something short, like data.txt.
  • Moving it to the root of the drive (e.g., C:\).
  • Copying it to a different folder or drive.

If you can’t rename because the error appears when you try to open it, use a file recovery tool or try opening it with a different application.

Fix 5: Disable Antivirus Temporarily

Security software can block file access. To test:

  1. Open your antivirus program.
  2. Look for a setting to temporarily disable real-time protection (often in “Settings” or “Protection”).
  3. Try the operation again.
  4. Re-enable protection immediately after.

If this fixes it, add an exclusion for the file or folder in your antivirus settings.

Frequently Asked Questions

Why does the error happen only with one file?

That points to a file-specific issue: it might be locked by a background process, corrupted, or have a name/path that violates Windows rules. Try copying it to a new location with a short name.

Can I recover data from a disk that shows this error?

Yes, in many cases. If the disk is not physically damaged, you can use file recovery software (like Recuva or PhotoRec) to scan the drive. If the disk is making clicking sounds, stop using it and consult a professional.

Does this error mean my hard drive is failing?

Not necessarily. It’s often a software issue. But if you get this error frequently with different files, run a SMART test (using tools like CrystalDiskInfo) to check the drive’s health.

How do I fix “Can’t read source file or disk” when copying from a CD or DVD?

Clean the disc, try a different optical drive, or copy the files to your hard drive first. Scratched discs can be partially read with software like IsoBuster.

What if the file is on a network drive?

Check your network connection, ensure the shared folder is accessible, and try mapping the drive to a letter. Also, ask the administrator if you have permission to read the file.

When to Seek Professional Help

If you’ve tried all the above and the error persists, the disk may have physical damage. Stop using the drive immediately to prevent further data loss. A professional data recovery service may be able to retrieve your files, but this can be costly. For most users, the fixes above resolve the issue.

Related

Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.